<?php/** * shuffle : 配列をランダムに入れ替える */$numbers = range(1, 20);shuffle($numbers);echo "-----" , PHP_EOL;foreach ($numbers as $number) {    echo "$number ";}echo PHP_EOL;echo "-----" , PHP_EOL;$strs = array('a','b','c','d','e');shuffle($strs);foreach ($strs as $str) {    echo "$str ";}echo PHP_EOL;